While mattresses can be constructed from a single layer of cotton or foam rubber or from a unitary block of springs covered in a padding material, improved comfort is achieved through the use of multiple layers. The properties and location of each layer within the mattress are selected to provide a desired level of comfort. Two common layers are foam layers and innerspring layers. Multiple foam layers can be used, with each foam layer having a desired density or firmness. An innerspring is provided as a single layer of multiple springs that are located within the mattress, typically sandwiched between layers of foam, that span substantially the entire width and length of the mattress. These innersprings can be contained within a unitary innerspring frame or placed in a plurality of separate spring fabric pockets. Therefore, the entire body of the user is supported by the innerspring layer.
Conventional innersprings are relatively large in diameter and height, have lower spring counts, i.e., total number of springs in the inner spring layers, and are constructed from wire having a gauge below 13. These conventional innersprings yield a relatively low level of comfort and support as a result of their size, stiffness and number. An attempt at improving the innerspring layer replaces the conventional innersprings with smaller innersprings. Each one of these smaller innersprings is referred to as a “microcoil”. A microcoil has a smaller diameter and height and is constructed from thinner and more flexible wire having a gauge above 14. The smaller size of the coils facilitates an increased number of coils in the innerspring coil layer. For example, a microcoil layer can contain 800 or more microcoils. Microcoil inner springs can be used in combination with a conventional innerspring as an additional comfort layer disposed between the conventional innerspring layer and the top surface or sleeping surface of the mattress. This comfort layer increases the comfort and pressure relieving qualities of the mattress.
The single layer of microcoils provides only a limited improvement to the mattress. In addition, the unitary layer of microcoils may not be optimal for adjustable bed applications. Therefore, arrangements of innerspring microcoils are desired that provide improved comfort and that work well with adjustable and articulating bed frames.